Connecticut just became the first state in the nation to require employers to provide workers with paid sick days. The new law — which also allows paid leave for a sick child or spouse — is controversial. Opponents attack it as big government run amok and say it will kill jobs. But it is the right thing to do, both as a matter of humane treatment of workers and public health. And while the law doesn’t cover everyone, it’s a step in the right direction and other states should follow Connecticut’s lead.

Millions of Americans work at jobs that do not offer them a paid day off when they get sick. In the private sector, nearly 40% of workers do not have paid sick leave. Not surprisingly, low-income workers are worst off. Among the bottom 25% of wage earners — those making $10.50 or less an hour — just 33% can take a paid day off when they are ailing.

That means that millions of Americans often have to go to work sick or in pain — a phenomenon known as presenteeism — or they may not be able to help family members who face medical emergencies. If they have no choice but to miss work, they risk being fired.

Advocates for paid sick leave point to the case of Hilda Pizarro. Pizzaro says she was suspended from her job cleaning houses for Merry Maids — which does not offer paid sick days — because she had to take her 2-year-old son to the hospital for emergency asthma treatment. While she was on suspension, she says, she was terminated.

Supporters of paid sick leave also argue that everyone benefits when sick people do not show up for work. Requiring paid sick leave “is good public policy and specifically good public health,” Governor Dan Malloy said when he signed Connecticut’s law last July. “Why would you want to eat food from a sick restaurant cook? Or have your children taken care of by a sick day-care worker? The simple answer is — you wouldn’t.”

Opponents of the bill, on the other hand, argue that it is big government regulation and insist it will kill jobs. They also worry about where the law will go next. Critics ask what the state will mandate next: paid vacations and coffee breaks?

Connecticut’s law is actually more narrowly drawn than a lot of the headlines suggest. It requires employers to give full-time workers up to five paid sick days a year when they are sick, or a child or spouse is — but it comes with a lot of exceptions. The law only applies to “service workers” and only to employers with 50 or more employees. There are carve-outs for manufacturers, national nonprofits, temporary workers and day laborers — none of whom are covered by the law.

The law’s narrow focus actually protects the state against job loss. States often compete heavily for manufacturing jobs and try to stop manufacturers from leaving. But these are just the companies that are not covered by the sick-leave law. The jobs that are covered — service jobs ranging from bellhop to butcher — are for the most part not geographically mobile. If a hotel in Hartford does not want to give its bellhops paid sick leave, it cannot exactly pack up and move to Phoenix.

But that mobility issue points to the new law’s weakness. Factory workers need paid sick leave too, but it is hard for any one state, especially in these economically competitive times, to impose new proworker rules on jobs that are mobile. What is really needed is a national paid-sick-leave law.

Connecticut may be the first state to require paid sick leave, but several cities have also made the change in recent years. San Francisco passed a law in 2006, and Washington and Milwaukee followed. Seattle adopted a paid-sick-leave law in September. There are bills pending in several states, from Massachusetts to California.

There is one more major force driving these proworker laws, along with compassion and public health, and it is a paradoxical one: the decline of labor unions. When unions were stronger, workers could count on getting benefits like paid sick leave through their labor contracts, negotiated by their unions. But these days, when the vast majority of workers do not have a union, they need to turn to the law to get protections they once got by contract.

Will paid-sick-leave laws lead to government-imposed coffee-break requirements? Not likely. But they could be a recognition that as unions decline, and as a weak economy increasingly gives employers the upper hand, lawmakers may need to take more responsibility for ensuring that working conditions are healthy, for everyone.